Materials requirements for light-weight, high-temperature composites and adhesives for aircraft and aerospace structural applications have led to the exploration of a number of polymeric systems which might be utilized. One of the most promising classes of candidate materials has been the aromatic heterocyclic polymers. Unfortunately, the most thermally stable systems in this class of materials are formed by condensation reactions with the evolution of volatile by-products. In the fabrication of reinforced composite structures, the volatile by-products, which are evolved, form voids which greatly weaken the structures. Accordingly, there is a real need for a heterocyclic oligomeric material which possesses all the required fabrication criteria and can be converted to a thermally stable, high molecular weight polymer by a non-volatile addition reaction.
It is an object of this invention, therefore, to provide ethynyl-substituted aromatic ortho-diamine compositions which can be used as endcapping agents for heterocyclic oligomers, thereby enabling such systems to cure by addition reactions.
Another object of the invention is to provide methods for preparing intermediates that are used in the synthesis of the endcapping agents.
A further object of the invention is to provide a method for synthesizing the endcapping agents.
Other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the accompanying disclosure.